From e5b306a082982cb98bc7ec48a382225522401a61 Mon Sep 17 00:00:00 2001 From: Kairui Song Date: Tue, 17 Oct 2023 09:17:28 +0800 Subject: [PATCH] mm/swap: avoid a xa load for swapout path A variable is never used for swapout path (shadowp is NULL) and compiler is unable to optimize out the unneeded load since it's a function call. The was introduced by 3852f6768ede ("mm/swapcache: support to handle the shadow entries"). Link: https://lkml.kernel.org/r/20231017011728.37508-1-ryncsn@gmail.com Signed-off-by: Kairui Song Reviewed-by: Matthew Wilcox (Oracle) Cc: Huang Ying Signed-off-by: Andrew Morton --- mm/swap_state.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/swap_state.c b/mm/swap_state.c index b3b14bd0dd64..ab79ffb71736 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -109,9 +109,9 @@ int add_to_swap_cache(struct folio *folio, swp_entry_t entry, goto unlock; for (i = 0; i < nr; i++) { VM_BUG_ON_FOLIO(xas.xa_index != idx + i, folio); - old = xas_load(&xas); - if (xa_is_value(old)) { - if (shadowp) + if (shadowp) { + old = xas_load(&xas); + if (xa_is_value(old)) *shadowp = old; } xas_store(&xas, folio);